The present invention relates to an electronic musical instrument of waveshape memory type with expression control for varying qualities of a produced musical tone, such as tone color, in response to operation of a performance controller such as a key on a keyboard or an expression pedal.
Prior electronic musical instruments have a waveshape memory serving as a sound source to store whole waveshape information of musical tones to be produced, the waveshape information being read out to generate corresponding musical tone signals. The musical instrument of this type is capable of producing musical tones of high quality as it stores and reads out musical tone waveshapes as they are. However, this known instrument meets difficulty in providing a so-called "touch response function" which can change qualities of a musical tone produced, such for example as tone color or timber, in response to the speed or strength of depression (hereinafter referred to as a "key depression touch") of keys of a keyboard. More specifically, the musical tone waveshapes as they are read out of the waveshape memory remain constant at all times. If the tone color of a musical tone were to be varied through the control of a key depression touch, the waveshape information as read out of the waveshape memory would need to be passed through a digital filter or an analog filter after the waveshape signal has been converted into an analog signal, the filter being controllable in response to the key depression touch. Therefore, the overall circuit arrangement required would become complicated.